Yogurt, a fermented dairy product, is an ancient foodstuff that has gained increasing popularity in recent years, particularly with the advent of such yogurt variants as lowfat and nonfat yogurts, frozen yogurts of various types and flavors, fruit-filled and other flavored yogurts and even drinkable yogurts and other yogurt-containing drinks.
To be called yogurt or have the word yogurt as part of its name any fermented dairy product sole in this country must be formulated and processed according to the definitions and limitations of the U.S. Food and Drug Administration's Standards of Identity for yogurt products as set out at 21 CFR .sctn..sctn. 131.200 et seq.
Yogurt products which meet the FDA's Standards of Identity are produced by culturing cream, milk, partially skimmed milk, skimmed milk or mixtures of these "optional dairy ingredients" to at least a given minimum quantity of titratable acidity using a characterizing bacterial culture that contains the lactic acid producing bacteria, Lactobacillus bulgaricus and Streptococcus thermophilus. The Standards of Identity also place strict limitations on the types and amounts of vitamins, other optional dairy and nondairy ingredients, flavoring additives, color additives and stabilizers which may be present, prescribe the percentages of milkfat and milk solids which yogurt products must contain and spell out how the product is to be treated before and after the bacterial culture is added. Given these strictures, and experience with one unsuccessful commercial attempt several years ago to formulate an aerosol dispensable yogurt product, persons skilled in the art of yogurt manufacture have considered it impossible to formulate a shelf-stable yogurt product which could be stored in and dispensed from an aerosol can and still meet the definitions and limitations of the Standards of Identity for yogurt products.
The known prior art gives no reason to suppose that this is not true; typically, patents directed to yogurt products of various kinds are silent with regard to aerosol dispensability.
U.S. Pat. No. 4,374,155, issued Feb. 15, 1983 to Igoe et al, for example, discloses "yogurt milk shake" formulations which contain a soya protein whipping agent and, as a stabilizer, xanthan gum with or without carboxymethylcellulose. These yogurt milk shakes:
". . . could be sold commercially in 1/2 pint to 1 pint containers sealed with sufficient headspace to allow for shaking by the end user/consumer, whereby air in the headspace is entrapped in the yogurt/milk mixture to produce the final product: a thickish, frosty shake", PA0 ". . . which will remain drinkable and not thicken with age, will hold fruit particles in suspension, and will not develop objectionable off-flavors . . . ", PA0 ". . . with no casein precipitate, no bitter aftertaste and a firm heavy body . . . ", PA0 "The important aspect of this invention is the use of the whey proteins, lactalbumin and lactalglobumin, with whey protein concentrate as the source, to maintain solubilization of casein to prevent high curd tension development by agglomeration of the casein colloid particles", PA0 ". . . a soft food mix or frozen confection, such as soft ice cream, milk shakes, yogurt, or the like", PA0 ". . . the constituents of such soft food products are mixed in large quantities at some central location and then shipped under refrigeration in pressurized containers to the individual shops where the product is sold. The product is often combined with nitrous oxide and/or Freon (Trademark) which expands the volume of the product. The amount of nitrous oxide or other gas added is usually expressed as `percentage overrun". PA0 "The gases usually are added to the soft food mix in the dispensing machine and particularly as the soft food mix moves under pressure from the refrigerated container within the machine to the dispensing valve. However, it is also possible, and preferable under most circumstances, to add the gases at the central location before the soft food mix is placed in the containers in which it is transported to the dispensing machines",
column 4, lines 16-21. It would appear that the substantial amount of milk (20-47%) required in Igoe et al's formulations to achieve a milkshake-type product would preclude packaging such formulations in aerosol cans from which a whipped product could then be dispensed.
U.S. Pat. No. 4,110,476, issued Aug. 29, 1978 to Rhodes, discloses liquid yogurt base and frozen yogurt mix formulations which will yield in the case of liquid yogurt a product:
column 1, lines 8-11, and in the case of frozen yogurt a product:
column 1, lines 11-13.
According to the Rhodes patent:
column 4, lines 38-43. The Rhodes patent contrasts this casein -solubilizing property of whey proteins in its yogurt formulations with what it intimates is the unacceptable behavior of hydrophillic gums or colloids such as sodium alginate and its derivatives, xanthan gum, Locust Bean gum, pectin and Guar gum, all of which are said to react with casein to ". . . form heavy weight colloid particles which are large in size and, hence, will precipitate more readily"; column 9, lines 11-36.
U.S. Pat. No. 3,961,494, issued June 8, 1976 to Schaefer et al, does speak of pressurized dispensing of:
column 1, lines 7-9. No formulation details are given, however, and in fact this mention of yogurt is made only in the context of large scale commercial retail operations in which:
column 1, lines 10-28. Hence, Schaefer et al's disclosure in this respect merely serves as a backdrop for its teaching of an improved dispensing machine for such commercially dispensed soft foods.
It is an object of this invention to provide shelf-stable aerosol dispensable yogurt products.
Another object of the invention is to provide unique stabilizer systems which permit yogurt and yogurt-containing products to be prepared as shelf-stable aerosol dispensable formulations useful as desserts and as toppings for other dessert items.
A further object of this invention is to provide shelf-stable aerosol dispensable yogurt products containing such stabilizer systems.
A still further object of this invention is to provide methods of formulating such shelf-stable aerosol dispensable yogurt products.
These and other objects, as well as the nature, scope and utilization of this invention, will become readily apparent to those skilled in the art from the following description and the appended claims.